Flexible fan

ABSTRACT

The invention relates to a flexible fan comprising, a boss portion and a plurality of fan blades radially extended from the boss portion and integrally formed therewith, the boss portion and the fan blades being of one piece construction and made of synthetic resin material, the flexible fan being characterized in that,  alpha  shows an angle of inclination of a wing chord against the rotational direction of the blade and  beta  shows an angle against the wing chord of a leading edge portion of the fan blades, and  alpha  &lt;/=  beta  is represented.

United States Patent 1191 Hori et al.

11 3,822,103 July 2, 1974 [5 FLEXIBLE FAN [75] Inventors: Takanobu Hori;Masaharu Hayashi, both of Toyota; Motoharu Yoshida, lchimiya, all ofJapan i 73 Assignee: Aisin SeikiKabushikiKaisha,

Kariya. Aichi Pref., Japan [22] Filed:' Dec. 26, 1972 1211 Appl.1\16.5311;,421

[30] Foreign Application Priority Data [51] Int. Cl. F04d 29/38 58 Fieldf Search 416/132, 240, 241A [56] References Cited UNITED STATES PATENTSAntoni 416/132 x Japan 47 4800 521'u.s.c1.. ..416/-132,416 240,416/2413,054,355 9/1962 Neely ..416/240x 3,409,968 1 1/1968 Denes' 3,584,9696/1971 Aiki ct a1. 416/132 FOREIGN PATENTS OR APPLICATIONS 2,013,48110/1970 Germany 416/132 Primary Examiner-Everette A. Powell, Jr.Attorney, Agent, or Firm-Pierce, Scheffler & Parker [57 ABSTRACT I Theinvention relates to a flexible fan/comprising, a boss portion and aplurality of fan blades radially extended from the boss portion andintegrally formed therewith, the boss portion and the fan blades beingof one piece construction and made of synthetic resin material,the'flexible fan being characterized in that, a

shows an angle of inclination of a wing chord against the rotationaldirection of the blade and B shows an angle against the wing chord of aleading edge portion of the-fan blades, and a 1 B is represented.

Clainis, 7 Drawing Figures PAIENIEDJuL 2:914 3.822.103

' sum 1 or 3 FIG.1

1 FLEXIBLE FAN BACKGROUND OF THE INVENTION that the road conditionsaresatisfactory for running of the vehicle, if circumstances require thevehicle to run on a flooded road not only in the rainy season, but alsoY in the normal state. In that case the water is driven up bythe frontportion of the tire that is, the lowest portion of the fan is deformedand a lower part of the fan blade is flooded, sothat the blade isunusually deformed by the impact force of the water. The fan issusceptible to damage by contacting the radiator.

Therefore, in the conventional fan a large gap between the blade and theradiator is necessary in order to prevent'the fan from contacting withthe radiator, or the thicknessof the leadingedge portion is reduced or areinforced material is supplied. However, the cooling efficiency of thevehicle engine is reduced and an unreasonable arrangement in the enginecompartment is necessary. The abovementioned drawbacks of the former isnot fully overcome by the latter and further the weight of the fan bladeis increased and the cooling efficiency of the vehicle engine is reducedin the latter.

SUMMARY OF THE INVENTION It is,itherefore, an object of the presentinvention to provide an improved fan assembly adapted for obviating theaforementioned drawbacks of the conventional fan assembly. I

It is another object of the present invention to provide an improved fanassembly for eliminating the displacement of thejleading edge portion ofthe blade toward the radiator when the blade encounters a flooded area.i c f It is still another object of the present invention to provide animproved fan assembly for raising the cooling efficiency of an engine byminimizing the gap between the radiator and the fan.

BRIEF DESCRIPTION OF THE DRAWINGS Various other objects," features andattendant advantages of this invention will be more fully appreciated asthe same becomes better understood from the follow- 2 FIG. 5 is adistributive view of pressure operating the blades, when blades areflooded;

FIG. 6 is a view showingthe deformed condition of blades when the bladesare flooded; and t I FIG. 7 is a view similar to that of FIG; 2,illustrating,

however, a fourth embodiment of this invention:

DESCRIPTION OF THE ILLUSTRATED I I EMBODIMENTS Referring now to thedrawings, and more particularly to FIG. 1 thereof, the fanassembly ofthis invention will be described hereinbelow in detail.

In this Figure, the reference numeral 10 designates a fan boss and aplurality of blades 11 are radially extended'from an outerperipheralportion 12 of the fan boss 10. The fan boss 10 and the blades 11 areintegrally formed and made of such as synthetic resin. The referencenumeral 13 isa pilot hole for connecting with a pulley seat, notshown,and a plurality of bolt holes 14 is provided on the fanboss 10.The ventilation isgenerally ventilated almost parallel. to a rotationalaxle, not shown, Accordingto FIG. 2, the incidence angle against arotational direction 15 of a warpedline 16 of the blades 11 in a leadingedge portion 18 is" zero or a little negative angle-is applied to theleading edge portion l8. That is to say, supposing that an angle ofinclination of a wing chord 17 against the rotational direction 15 ofthe warped line 16v is a and angle 6,, against the wing chord 17 of theleading edge portion 18 is nearly equal to the angled, or the angle [3,is only larger-than the angle a Next referring to FIG. 2, the referencenumeral 18a shows a leadingedge portion of a conventional blade, andassuming that an angle against a wing chord 17a of the leading edgeportion 18a against the extension of the warped line 16 is [32, an anglea of inclination of the wingichord 17a againstthe rotational direction15, is larger than the angle'fi of the leading-edge portion 18a and theleading edge portion 18a is spread from the rotational direction 15 inthe upper direction (toward the radiator, not shown). A groove'20 isprovided on the middle portion of the blade 11 soas to easily bend atrailingedge portion 19 of the blade 11 when the hydraulic pressureorwind pressure is operated to the blade-'11 as shown in .FIGSJI and 2.An arc-shaped groove or a thin face 21 may be formed on the trailingedge portion 19 of the blade in order to specially bend ing detaileddescription when considered in connection with the accompanyingdrawings, wherein like reference characters designate like orcorresponding parts throughout the several views and wherein:

FIG. 1 isa front view of the fan assembly of this inve'ntion,. butpartially illustrated;

FIG.' 2 is a sectional view taken along the line II'-II of FIG. 1;

the trailing edge portion 19 thereof as viewed in FIG. 7.

As to the arrangement of the groove 20, it can be on a surface 22 or theinside surface 23, or on both the sur- 1 face 22 and the surface 23 asshownin FIG. 3. When the groove 20 is, however, provided on the surface22 the ventilation speed of the surface 22 is swifter than I when on theinside 23 in the operating state, namely, Reynolds number ishigh and thefan efficiency is re-' I duced, therefore it is desirable to provide thegroove 20 I on the inside 23. It is not necessary to provide the in thisinvention as viewed in FIG. 7.

When the blade 11 reaches a flooded area 24 in the increasing state ofthe number of fan rotation as seen groove 20, thearc-shaped groove, orthe thin face 21 in FIG. 6, the impact force at this moment and theincreasing pressure force on the inside 23 of the blade 11 are verylarge and the positive pressure is normally applied to the inside 23 ofthe leading edge portion .18 as shown in FIG. 5, but the negativepressure is supplied thereto in this invention. The positive pressure isprovided on the inside 23 of the trailing edge portion 19 also in thenormal blade or in the blade 11 according to this invention.

However, when the blade 11 reaches the flooded area 24 the blade 11 isbent almost parallel to the warped line 16a of the blade 11 in thenormal fan and passes the flooded area 24, and then the blade 11 isrestored to the original state.

The warped line 16 of the leading edge portion 18 of the blade 11 isalmost parallel'to or at a slight negative angle to the rotationaldirection so that only the impact force is applied to the leading edgeportion 18 also at the moment of arrival at the flooded area 24 orthereafter, and the water pressure is supplied to the inside 23 of theblade 11 at the trailing edge portion 19 as viewed in FIG. 5 so thatonly the trailing edge portion 19 tends to bend upwards in FIG. 6. Thebending force is, however, absorbed by the groove 20 provided on theinside 23 of the blade 11. Therefore, the bending force does notinfluence the leading edge portion 18 and so the leading edge portion 18of the blade 11 is not displaced with respect to face of the fan.

The result of the experiment between the fan accord- I ing to thisinvention and the fan according to conventional type is showed asfollows;

Fan of this leading edge of fan (number of fan rotations 3000-3500r.p.m.)

The abovementioned rate to the chord length of the bent portion of theleading edge shows the rate against the chord length of the lengthprojected to the bent portion of the leading edge on the chord length.

lt is desirable, that the rate to the chord length'of one piececonstruction and made of synthetic res- Y inous material; said flexiblefan having an angle a between a wing chord and the rotational directionof said fan blades and an angle B between said wing chord and a tangentline of a warped line in the'leading edge of a leading edge portion inwhich a is not greater than B, said warped line having a bent portion atsaid leading edge portion, and the bending rate of said bent portion insaid leading edge portion against a chord length of said fan blade isbetween 8 and percent.

2. The flexible fan as set forth in claim 1, wherein a groove isprovided on said fan blade so that the trailing bent portion is 8-30percent. But when the rate reaches over 8-3O percent the coolingefficiency becomes bad, and when the rate is under 20-24 percent theeffect for preventing the bending becomes-little.

Obviously many changes and modifications of the edge portion of said fanblade is easily bent.

3. The flexible fan as set forth in claim 2, wherein said groove isformed on said trailing edgeportion.

4. The flexible fan as set forth in claim 2, wherein a thin face isformed on said trailing edge portion.

5. A flexible fan comprising:

a boss portion; and

a plurality of fan blades radially extended from said boss portion andintegrally formed therewith; said boss portion and plurality of fanblades being of one piece construction and made. of synthetic resinousmaterial;

said flexible fan having anangle a between a wing chord and therotational direction of said fan blades and an angle [3 between saidwing chord and a tangent line of a warped line in the leading edge of aleading edge portion in which a is not greater than B, said warped linehaving a bent portion at said leading edge portion, and the bending rateof said bent portion in said leading edge portain against a chord lengthof said fan blade is between 20 and 24 percent.

6. The flexible fan as set forth in claim 5, wherein a groove isprovided on said fan blade so that the trailing edge portion of said fanblade is easily bent.

7. The flexible fan as set forth in claim 6, wherein said groove isformed on said trailing edge portion.

8. The flexible fan as set forth in claim 6, wherein a thin face isformed on said trailing edge portion.

1. A flexible fan comprising: a boss portion; and a plurality of fanblades radially extended from said boss portion and integrally formedtherewith; said boss portion and plurality of fan blades being of onepiece construction and made of synthetic resinous material; saidflexible fan having an angle Alpha between a wing chord and therotational direction of said fan blades and an angle Beta between saidwing chord and a tangent line of a warped line in the leading edge of aleading edge portion in which Alpha is not greater than Beta , saidwarped line having a bent portion at said leading edge portion, and thebending rate of said bent portion in said leading edge portion against achord length of said fan blade is between 8 and 30 percent.
 2. Theflexible fan as set forth in claim 1, wherein a groove is provided onsaid fan blade so that the trailing edge portion of said fan blade iseasily bent.
 3. The flexible fan as set forth in claim 2, wherein saidgroove is formed on said trailing edge portion.
 4. The flexible fan asset forth in claim 2, wherein a thin face is formed on said trailingedge portion.
 5. A flexible fan comprisinG: a boss portion; and aplurality of fan blades radially extended from said boss portion andintegrally formed therewith; said boss portion and plurality of fanblades being of one piece construction and made of synthetic resinousmaterial; said flexible fan having an angle Alpha between a wing chordand the rotational direction of said fan blades and an angle Betabetween said wing chord and a tangent line of a warped line in theleading edge of a leading edge portion in which Alpha is not greaterthan Beta , said warped line having a bent portion at said leading edgeportion, and the bending rate of said bent portion in said leading edgeportain against a chord length of said fan blade is between 20 and 24percent.
 6. The flexible fan as set forth in claim 5, wherein a grooveis provided on said fan blade so that the trailing edge portion of saidfan blade is easily bent.
 7. The flexible fan as set forth in claim 6,wherein said groove is formed on said trailing edge portion.
 8. Theflexible fan as set forth in claim 6, wherein a thin face is formed onsaid trailing edge portion.